SCHEDULE-INDUCED POLYDIPSIC CHOICE BETWEEN COCAINE AND LIDOCAINE SOLUTIONS - CRITICAL IMPORTANCE OF ASSOCIATIVE HISTORY

Two groups of rats given daily, 3-h, intermittent food-pellet sessions , which induced polydipsia, drank either cocaine (COG) or lidocaine (L IDO) solutions, Then water was made available concurrently, but neithe r group preferred drug solution, When drug was presented in a glucose- saccharin vehicle, which was subsequently faded out, both the COC and LIDO groups acquired a strong preference for drug solution rather than water, Half of each group was continued, and half was directly faded to a preference for the other drug solution rather than water, Then CO C and LIDO solutions were available concurrently and animals overwhelm ingly preferred the drug solution that historically had been associate d with the glucose-saccharin vehicle, Finally, the COG-preferring and LIDO-preferring groups had the concentrations of their preferred drug increased step-wise several times and preferences were maintained, Thu s, acquired drug preferences remained stable as preferred drug concent ration was increased, making it more bitter than the nonpreferred drug , The abuse potential of COC affords it little advantage over LIDO in the institution and maintenance of oral drug preference, suggesting th at the post-ingestive pharmacological action of a drug is less importa nt for acquiring drug-taking than is a history of associating the drug with another reinforcing event.